Heat treatment unit and heat treatment method

ABSTRACT

A heat treatment unit comprises a heat plate made of aluminum nitride which is excellent in heat conductivity and strength inside thereof. The entire circumference of the heat plate is supported by a supporting member which is excellent in thermal insulation. The heat treatment unit is equipped with a nozzle for blowing dry air against the reverse side of the heat plate. When a temperature of the heat plate is lowered, the dry air is blown from the nozzle, thereby quickly lowering the temperature of the heat plate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat treatment unit used toperform heat treatment on a substrate, and a heat treatment method.

[0003] 2.Description of the Related Art

[0004] In a photo-resist treatment step in a process, of semiconductordevice fabrication, various kinds of heat treatments, such as heattreatment after a resist-coating on the surface of a semiconductor wafer(described as “a wafer” hereinafter) called prebaking and heat treatmentafter an exposure of a pattern called post-exposure baking, areperformed.

[0005] Such heat treatments are generally performed in a heat treatmentunit. The heat treatment unit comprises a disk shaped heat plate withsome thickness made of aluminum-in a treatment case, and performs heattreatment on the wafer by putting the wafer, which is to undergo heattreatment, on the-heat plate and then by heating the heat plate to apredetermined temperature by a heating element embedded in the heatplate.

[0006] Further, there is a case where a temperature during heattreatment varies corresponding to types of semiconductor device to beformed, resist solution and process, such as heating the wafer to 140°C. or heating the wafer to a lower temperature, 90° C., for example. Inthis case, when the heat plate which has been undergoing heat treatmentat 140° C., for example, is changed to the one to be heated at 90° C.,it is inevitable to once lower the temperature of the heat plate, forexample, to 90° C. In such situations, a conventional heat treatmentunit of this type is not especially provided with a mechanism forcooling, or the like.

SUMMARY OF THE INVENTION

[0007] It is necessary to vary the temperature of the heat plate sincethe heat treatment temperature varies corresponding to types ofsemiconductor device to be formed, resist solution and process. On thisoccasion, it is preferable to raise and lower the temperature of theheat plate quickly in order to improve a throughput in waferfabrication.

[0008] However, heat exchange is not smoothly performed in, such a,manner that heat escapes from the outer peripheral portion of the heatplate and below the heat plate when the temperature of the heat plate israised, and heat is accumulated in the heat treatment unit when thetemperature of the heat plate is lowered, thereby requiring long time toraise and lower the temperature of the heat-plate.

[0009] In addition, when the heat plate is cooled to the predeterminedtemperature, heat is accumulated not only in a supporting member whichsupports the heat plate but also in an outer circumferential wall whichsurrounds an outer circumference of the supporting member if performedsimply with spontaneous cooling, which is undesirable since considerablylong time is required to make the temperature of the surface portions ofthe heat plate uniform after the heat plate is heated up to thepredetermined temperature.

[0010] An object of the present invention is to provide a heat treatmentunit in which a temperature of a heat plate can be raised and loweredquickly compared with the conventional heat treatment unit, and a heattreatment method.

[0011] A first aspect of the present invention is a heat treatment unitin which a substrate is heated on a heat plate, comprising a supportingmember which supports at least the peripheral portion of the heat plate,material of the supporting member being thermal insulating material.

[0012] A second aspect of the present invention is a heat treatment unitunit in which a substrate is heated on a heat plate, comprising asupporting member which supports at least the peripheral portion of theheat plate, material of the supporting member being thermal insulatingmaterial, and further comprising gas supply means for blowing gas forcooling against the reverse side of the heat plate.

[0013] A third aspect of the present invention is a heat treatment unitin which a substrate is heated on a heat plate, comprising an outercircumferential wall surrounding the outer circumference of a supportingmember which supports the heat plate, and a fin provided on the surfaceof the outer circumferential wall.

[0014] A fourth aspect of the present invention is a heat treatment unitin which a substrate is heated on a heat plate, comprising an outercircumferential wall surrounding the outer circumference of a supportingmember which supports the heat plate, and a tube provided to havecontact with the surface of the outer circumferential wall, in whichfluid for cooling circulates.

[0015] A fifth aspect of the present invention is a method of heatingwith a substrate placed on a heat plate, comprising the steps of closinga space below the heat plate when the substrate is heated and openingthe space below the heat plate when the heat plate is cooled.

[0016] According to the present invention, heat accumulated in the heatplate can be inhibited from dissipating from the outer peripheralportion of the heat plate since material of the supporting member isthermal insulating material, whereby a temperature of the heat plate canbe raised quickly while the temperature of the surface portion of theheat plate can be kept uniform during heat treatment.

[0017] According to the present invention, by blowing gas for coolingagainst the reverse side of the heat plate, heat accumulated in the heatplate is rapidly diminished by the gas when the heat plate is cooled,thereby enabling the heat plate to be cooled more quickly than theconventional one.

[0018] Further, according to the present invention, heat capacity of theouter circumferential wall can be decreased by, virtue of the finprovided on the surface of the outer circumferential wall. Furthermore,the surface area of the outer circumferential wall is increased, whichimproves the heat-dissipation efficiency of heat which is accumulated inthe outer circumferential wall. As a result, the heat plate, supportedby the supporting member can be more quickly cooled than theconventional one.

[0019] According to the present invention, heat accumulated in the outercircumferential wall is rapidly diminished since a tube, in which fluidfor cooling circulates, is provided, thereby improving a speed oflowering the temperature of the heat plate arranged inside of the outercircumferential wall, compared with the conventional one.

[0020] According to the present invention, when the substrate is heated,the substrate can be heated at a predetermined temperature by closing aspace below the heat plate to retain heat therein, which makes itpossible to raise the temperature more quickly than the conventionalone. When the heat plate is cooled, it is possible to lower thetemperature more quickly than the conventional one since the space belowis opened. Therefore, it takes less time to change setting oftemperature of the heat plate, resulting in the improvement of athroughput.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other features of the invention and the concomitantadvantages will be better understood and appreciated by persons skilledin the field to which the invention pertains in view of the followingdescription given in conjunction with the accompanying drawings whichillustrate preferred embodiments.

[0022]FIG. 1 is a plane view showing an appearance of a coating anddeveloping system provided with a post-exposure baking unit according tothe present invention;

[0023]FIG. 2 is a front view of the coating and developing system inFIG. 1;

[0024]FIG. 3 is a rear view of the coating and developing system in FIG.1;

[0025]FIG. 4 is an explanatory view of a vertical section of thepost-exposure baking unit according to the present invention;

[0026]FIG. 5 is an explanatory view of the post-exposure baking unitaccording to the present invention, viewing its plane state;

[0027]FIG. 6 is an explanatory view showing a state where gas is blownagainst the reverse of a heat plate in the post-exposure baking unitaccording to the present invention, taking its side view;

[0028]FIG. 7 is an explanatory view of a vertical section of thepost-exposure baking unit in the case of providing venting portions onthe peripheral portion of a base plate below the heat plate;

[0029]FIG. 8 is an enlarged explanatory view in the case of attachingcover members to the venting portions of the base plate below the heatplate in the post-exposure baking unit in FIG. 7;

[0030]FIG. 9 is a sectional explanatory view of a post-exposure bakingunit according to another embodiment of the present invention, takingits side view;

[0031]FIG. 10 is an explanatory views of a vertical section of an outercircumferential wall in the post-exposure baking unit in FIG. 9;

[0032]FIG. 11 is an explanatory view of the post-exposure baking unitaccording to another embodiment of the present invention, viewing itsplane state;

[0033]FIG. 12 is an explanatory view showing a state where air is blownagainst the reverse of a heat plate and against the outercircumferential wall in the post-exposure baking unit according toanother embodiment of the present invention, taking its side view;

[0034]FIG. 13 is an enlarged explanatory view explaining a case ofproviding tubes, in which fluid for cooling circulates, in grooveportions on the outer circumferential wall in the post-exposure bakingunit according to another embodiment of the present invention;

[0035]FIG. 14 is an enlarged explanatory view explaining a case ofproviding the tubes, assuming that the cross-sectional shape of thegroove portions on the outer circumferential wall is half-round;

[0036]FIG. 15 is an enlarged explanatory view explaining a case wherethe cross-sectional shape of the tube provided in the groove portion onthe outer circumferential wall is a rectangle;

[0037]FIG. 16 is a sectional explanatory view of the post-exposurebaking unit according to another embodiment of the present invention,which is provided with an exhaust duct below the heat plate, taking itsside view; and

[0038]FIG. 17 is an enlarged explanatory view explaining a case ofproviding a flow path for fluid for cooling inside of the outercircumferential wall.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT

[0039] A preferred embodiment of the present invention will be describedbelow with reference to the accompanying drawings. FIG. 1 is a planeview of a coating and developing system 1 comprising a post-exposurebaking unit as a heat treatment unit according to the embodiment. FIG. 2is a front view of the coating and developing system 1 and FIG. 3 is arear view of the coating and developing system 1.

[0040] As shown in FIG. 1, the coating and developing system 1 has astructure in which a cassette station 2 for carrying, for example, 25wafers from/to the outside to/from the coating and developing system 1in the unit of cassette and for carrying the wafers W into/from acassette C, a process station 3 in which various kinds of multi-tieredtreatment units for performing predetermined treatments one by one inthe coating and developing process are disposed, and an interfacesection 4 for receiving and delivering the wafer W from/to an alignerwhich is not shown and provided adjacent to the process station 3, areintegrally connected.

[0041] In the cassette station 2, a plurality of cassettes C are wellmounted at predetermined positions on a cassette mounting table 5serving as a mounting portion in a line in an X-direction (a verticaldirection on FIG. 1). Further, a wafer carrier 7, which is transferablein the direction of alignment of the cassettes (the X-direction) and inthe direction of alignment of the wafers W housed in the cassette C (aZ-direction; a vertical direction), is provided to be movable along acarrier guide 8 and is selectively accessible to the respectivecassettes C.

[0042] The wafer carrier 7 is structured so as to access also analignment unit 32 and an extension unit 33 which are included in a thirdtreatment unit group G3 on the side of the process station 3 as will bedescribed later.

[0043] In the process station 13, a main carrier unit 13 is provided inthe center part thereof, and various kinds of treatment units aremulti-tiered on the periphery of the main carrier unit 13 to composetreatment unit groups. In the coating and developing system 1, there arefour treatment unit groups G1, G2, G3, and G4, and the first and thesecond treatment unit groups G1, G2 are disposed on the front side ofthe coating and developing system 1, the third treatment unit group G3is disposed adjacent to the cassette station 2, and the fourth treatmentunit group G4 is disposed adjacent to the interface section 4. Further,as an option, a fifth treatment unit group G5 depicted by broken linescan be additionally arranged on the rear side of the coating anddeveloping system 1.

[0044] In the first treatment unit group GI, as shown in FIG. 2, twokinds of spinner-type treatment units, for example, a resist coatingunit 15 in which the wafer W undergoes resist coating, and a developingunit 16 in which the wafer W undergoes treatment with a developingsolution supplied are two-tiered in the order from the bottom. Also inthe case of the second treatment unit group G2, a resist coating unit 17and a developing unit 18 are similarly two-tiered in the order from thebottom.

[0045] In the third treatment unit group G3, as shown in FIG. 3, acooling unit 30 for cooling the wafer W, an adhesion unit 31 forincreasing the fixability between a resist solution and the wafer W, thealignment unit 32 for aligning the wafer W, the extension unit 33 forkeeping the wafer W waiting, prebaking units 34, 35 for drying a thinnersolution after the resist coating, and postbaking units 36, 37 forperforming heat treatment after developing and so on are, for example,eight-tiered in the order form the bottom.

[0046] In the fourth treatment unit group G4, a cooling unit 40, anextension and cooling unit 41 for spontaneously cooling the housed waferW, an extension unit 42, a cooling unit 43, post-exposure baking units44, 45 according to the embodiment for performing heat treatment afterexposure treatment, and postbaking units 46, 47 and so on are, forexample, eight-tiered in the order from the bottom.

[0047] Then, a wafer carrier 50 is provided in the center part of theinterface section 4. The wafer carrier 50 is structured so as to bemovable in the X-direction (the vertical direction on FIG. 1) and theZ-direction (the vertical direction), and to be rotatable in a θdirection (a rotational direction about an axis Z), so that it cansmoothly access the extension and cooling unit 41, the extension unit 42which are included in the fourth treatment unit group G4, a peripheralaligner 51, and the aligner which is not shown.

[0048] Next, the post-exposure baking unit 44 serving as the heattreatment unit will be described in detail. As shown in FIG. 4, in acasing 61, the post-exposure baking unit 44 is composed of a lid body 62which is disposed on the upper side of the casing and verticallymovable, and a heat plate accommodating portion 63 which is positionedon the lower side thereof and forms a treatment chamber S integrallywith the lid body 62.

[0049] The lid body 62 has a substantially conical shape in which theheight thereof is gradually increased toward its center, and is providedwith an exhaust portion 62 a at the top portion thereof so that anatmosphere in the treatment chamber S is uniformly exhausted through theexhaust portion 62 a.

[0050] The heat plate accommodating portion 63 comprised an externalcase 64 of substantially cylindrical shape, a disk-shaped heat plate 70disposed in the case 64, and a support 65 serving as a supporting memberwhich supports the peripheral portion of the heat plate 70 and is madeof polyimide-base or fluorine-base synthetic resin which is excellent inthermal insulation such as PBI (polybenzoimidazole) and PTFE(polytetrafluoroethylene).

[0051] The support 65 is formed in the shape of a ring so as to closelycome into contact with the entire peripheral portion of the heat plate70. Further, fluorine synthetic resin known as thermal insulatingmaterial is used, thereby inhibiting heat of the heat plate 70 fromdissipating from the peripheral portion of the heat plate in the heattreatment process. Therefore, the wafer W placed on the heat plate 70 isuniformly heated since the temperature of the surface portion of theheat plate 70 is kept uniform. Incidentally, the support 65 is supportedwith cylindrical supporting stands 67. Moreover, the support 65 isprovided with blow-out ports 66 as depicted in FIG. 5, whereby it ispossible to blow, for example, air, inactive gas or the like toward theinside of the treatment chamber S.

[0052] The heat plate 70 is made of, for example, aluminum nitride whichis excellent in heat conductivity and strength so as to be quicklyraised and lowered the temperature thereof and to be made thin, and thethickness thereof is, for example, 3 mm which is thinner than theconventional one.

[0053] On the reverse side of the heat plate 70, a heater, for example,in which a heating wire is wound on a copper plate as that in theconventional one, is not embedded, but a heater 71 made of silver whichgenerates heat by an electric feed is, for example, concentricallyprinted as heat source. Therefore, the thickness of the heater 71 isnearly zero, and even if with the heat plate 70 added, it is about 3 mmwhich is thin.

[0054] Below the heat plate 70, attached is a base plate 73 with holesprovided with a large number of venting portions 72 such as, forexample, a punching metal, to form a space section T surrounded with thebase plate 73, the heat plate 70, and the support 65.

[0055] On the base plate 73, nozzles 74, which blow gas for cooling, forexample, air at room temperature such as 23° C. toward the reverse sideof the heat plate 70 in a vertical direction, are provided at, forinstance, eight positions. As shown in FIG. 5, each four of the nozzles74 are concentrically arranged and the arrangement thereof is set not.to overlap with the positions of temperature sensors 75 for measuring atemperature of the heat plate 70 (depicted by x in FIG. 5) when viewingits plane state. Each of the nozzles 74 is connected by an air supplyduct 76, and respective air having the same wind speed is to be blownagainst the reverse side of the heat plate 70 from each of the nozzles74 when the air is supplied from the outside of the casing 61.Incidentally, as for the air, it is preferable to use dry air with lowhumidity or the like.

[0056] On the heat plate 70, holes 82, through which three hoisting andlowering pins 81 for hoisting and lowering the wafer W project from theupper surface of the heat plate 70, are provided at three portions.Moreover, between the respective holes 82 and the base plate 73,vertically disposed are respective cylindrical guides 83 for isolatingan atmosphere from the nozzles 74 by covering the outer circumference ofthe hoisting and lowering pins 81. By virtue of these guides 83, thevertical movement of the hoisting and lowering pins 81 is not affectedby various cables or the like wired beneath the heat plate 70, andadditionally, the air which is blown from the nozzles 74 can beprevented from discharging through the holes 82 toward the wafer W.Incidentally, hoisting and lowering pins 81 are vertically movable by anappropriate drive unit 84 such as an electric motor.

[0057] An appropriate exhaust port 64 a is provided on the circumferenceof the lower portion of the case 64, while an appropriate exhaust port61 a is also formed correspondingly on the side of the lower portion ofthe casing 61 in the post-exposure baking unit 44, and the exhaust port61 a is connected with an exhaust duct 85 leading to an exhaust portion(not shown) which intensively exhausts air from other treatment units inthe coating and developing system 1.

[0058] Next, a function of the post-exposure baking unit 44 serving as aheat treatment unit as structured above will be described together witha coating and developing process for the wafer W performed in thecoating and developing system 1.

[0059] First, the wafer carrier 7 takes out an unprocessed wafer W fromthe cassette C to carry it into the alignment unit 32 included in thethird treatment unit group G3. Second, the wafer, of which alignment iscompleted by the alignment unit 32, is sequentially transferred to theadhesion unit 31, the cooling unit 30, the resist coating unit 15 or 17,and the prebaking unit 34 or 35 by the main carrier unit 13, to undergopredetermined treatment. After that, the wafer W is transferred to theextension and cooling unit 41.

[0060] Then, the wafer W is taken out of the extension and cooling unit41 by the wafer carrier 50, and thereafter, transferred through theperipheral aligner 51 to the aligner which is not shown. The wafer W, ofwhich exposing treatment is completed, is transferred to the extensionunit 42 by the wafer carrier 50 and held in the main carrier unit 13thereafter. And subsequently, the wafer W is, transferred to thepost-exposure baking unit 44 or 45.

[0061] Next, traces of the wafer W in the post-exposure baking unit 44will be explained in detail.

[0062] First, the wafer W which has completed its pretreatment iscarried into the post-exposure baking unit 44 by the wafer carrier 50and is delivered to the hoisting and lowering pins 81 which ascend andkeep waiting in advance. Then, the wafer W comes down in accordance withthe descent of the hoisting and lowering pins 81 and is located on theheat plate 70. At this time, the wafer W is heated up to 140° C. bymeans of heat with, for example, the heater 71. Incidentally, in thisheating process, a solvent or the like which is evaporated from thesurface of the wafer is exhausted from the exhaust port 62 a. Afterheating of prescribed time, the hoisting and lowering pins 81 againascend to support the wafer and leave it with the main carrier unit 13so that the wafer is carried out to the outside of the post-exposurebaling unit 44.

[0063] Now, turning to a temperature of the post-exposure baking afterexposure varies corresponding to types of process, resist and so on. Infact, there is a case of not only heating at 140° C. as described above,but also heating at a lower temperature, for example, at 90° C. In thiscase, it is inevitable to quickly cool the heat plate 70 to makepreparations for heating at 90° C., and the post-exposure baking unit 44according to the present embodiment can desirably cope with suchlowering of the temperature of the heat plate.

[0064] More specifically, after the completion of heat treatment of thewafer W which is the last one of a lot that is to undergo heat treatmentat 140° C., air at room temperature is blown against the reverse side ofthe heat plate 70 from the nozzles 74, as shown in FIG. 6.

[0065] Then, the heat plate 70 is cooled immediately by the air at roomtemperature which is blown against the reverse thereof, since the heatplate 70 is formed to be thin by the use of aluminum nitride which isexcellent in heat conductivity.

[0066] Conversely, there is also a case where the wafer is heated at280° C. depending on a recipe. In this case, it is necessary to quicklyheat the heat plate 70 to make preparations for heating at 280° C. Sincethe heat plate 70 with excellent heat conductivity is used as describedabove, and besides, the heat plate 70 is supported by the support 65having the excellent thermal insulation property, whereby thetemperature of the heat plate 70 can be raised quickly by the heater 71printed on the underneath surface thereof than the conventional one.

[0067] According to the above-mentioned embodiment, in the heattreatment process in the post-exposure baking unit 44, heat of the heatplate 70 is inhibited from dissipating since the heat plate 70 issupported by the support 65 made of thermal insulating material, therebyimproving a speed of raising the temperature of the heat plate 70 whilekeeping the temperature of the surface portion of the heat plate 70uniform so as to uniformly heat the wafer W.

[0068] Further, since the heat plate 70 is formed thinner than theconventional one and aluminum nitride having excellent heat conductivityis used for its own material, the heat plate 70 increases responsivenessthereof and can be raised and lowered quickly the temperature thereof.Furthermore, the heat plate 70 is made thin, whereby the entirepost-exposure baking unit 44 can be compact.

[0069] The venting portions 72 of the base plate 73 which forms thespace section T below the heat plate 70 described above are permanentlyopened, but they can be so modified that the venting portions 72 areoccasionally opened and closed by attaching appropriate cover members orthe like thereto to shut the space section T. The space section T isopened and closed upon necessity as described above, so that when thewafer W undergoes heat treatment, the venting portions 72 are closed toretain heat inside of the space section T, thereby performing heattreatment on the wafer W with stability at a predetermined temperature.Moreover, when the temperature of the heat plate 70 is raised, it ispossible to raise the temperature quickly since heat-dissipation fromthe space section T can be prevented by closing the venting portions 72.On the other hand, when the heat plate 70 is cooled, heat can be quicklyescaped by opening-the space section T.

[0070] In order to realize such function, venting portions 90, forexample, are provided on the peripheral portion of the base plate 73forming the space section T below the heat plate 70 as shown in FIG. 7and relief valves 91 are attached as shown in FIG. 8. The relief valves91 have cover members 92 flexibly opening and closing the ventingportions 90 and are rotatable about rotating portions 93. Additionally,the cover members 92 are biased by urging members (not shown) such assprings so as to close the venting portions 90 in a primary state. Bythe relief valves 91 having such structure, the venting portions 90 areopened against biasing pressure of the urging members when pressure fromabove, that is, from the space section T is exerted. Namely, in the caseof lowering the temperature of the heat plate 70, when gas for coolingis blown from the nozzles 74, internal pressure of the space section Trises, thereby opening the cover members 92 and releasing heat togetherwith outflow of the gas. On the other hand, when the temperature of theheat plate 70 is raised or during the heat treatment process, outflow ofthe gas from the nozzles 74 is brought to stop, whereby the covermembers 92 close the venting portions 90 by urging pressure to preventheat of the heat plate 70 from escaping. As a result, raising andlowering of the temperature of the heat plate 70 is expedited, whichmakes it possible to more quickly raise and lower the temperature of theheat plate 70. Incidentally, it should not be limitedly understood thata relief valve which realizes the above-mentioned function has thestructure as is shown in the relief valve 91.

[0071] Additionally, although the aforesaid present embodiment isrealized as a heat treatment unit capable of performing post-exposurebaking, other heat treatment units such as prebaking unit and the likecan be naturally employed. Further, although a substrate is the wafer Win the above, it is also applicable to heat treatment units with otherrectangular substrates, for example, an LCD substrate.

[0072] By contacting the support 65 closely with the heat plate 70 tosupport the entire circumference of the heat plate 70, heat from theheat plate 70 is inhibited from dissipating, thereby raising thetemperature of the heat plate 70 quickly, and additionally improving theuniformity of the surface temperature of the heat plate 70.

[0073] Since material of the heat plate 70 is of aluminum nitride, heatconductivity is improved and the temperature of the heat plate 70 can beraised and lowered quickly than the conventional one. Moreover, sincealuminum nitride is more excellent also in strength compared withaluminum used conventionally, the heat plate 70 can be made thin inthickness, which makes it possible to increase the responsiveness toheat, and raise and lower the temperature of the heat plate 70 quickly.

[0074] It takes less time to change setting of temperature than that inthe conventional one, resulting in a contribution to the improvement ofa throughput. In addition, since the uniformity of the surfacetemperature of the heat plate is improved, an increase in yield can bealso expected.

[0075] Next, another embodiment of the present invention will bedescribed hereunder. As shown in FIG. 9, in a casing 161, apost-exposure baking unit 141 is composed of a lid body 162 which isdisposed on the upper side of the casing and movable upward anddownward, and a heat plate accommodating portion 163 which is positionedon the lower side thereof and forms a treatment chamber S integrallywith the lid body 162.

[0076] The lid body 162 has a substantially conical shape in which theheight thereof is gradually increased to its center, and is providedwith and exhaust portion 162 a at the top portion thereof, so that anatmosphere in the treatment chamber S is uniformly exhausted through theexhaust portion 162 a.

[0077] The heat plate accommodating portion 163 comprises a disk-shapedheat plate 170 in the center thereof, a support 165 serving as asupporting member which supports the peripheral portion of the heatplate 170 and is excellent in thermal insulation, an outer supportingmember which supports the peripheral portion of the heat plate 170 andis excellent in thermal insulation, an outer circumferential wall 166 ofsubstantially cylindrical shape which surrounds the outer circumferenceof the support 165 and a substantially cylindrical case 164 surroundingthe outer circumference of the heat plate accommodating portion 163. Thesupport 165 is supported with supporting stands 168 of substantiallycylindrical shape.

[0078] The outer circumferential wall 166 is made of, for example,aluminum and has a shape of almost cylinder as shown in FIG. 10. On theoutside surface of the outer circumferential wall 166, provided arering-shaped groove portions 166 b, to thereby form fins 166 a fordecreasing heat capacity of the outer circumferential wall 166 andincreasing the surface area thereof. A plurality of the groove portions166 b are formed with a predetermined width and a predetermined depthalong the circumference of the outer circumferential wall 166. Thegroove portions 166 b are provided parallel to each other at equallyspaced intervals. As a consequence, an amount of heat accumulated in theouter circumferential wall 166 is decreased and at the same time theheat-dissipation efficiency is improved. On the upper surface of theouter circumferential wall 166, provided are blow-out ports 166 c, whichmakes it possible to blow, for example, air, inactive gas or the liketoward the inside of a treatment chamber S.

[0079] Further, nozzles 167, which blow gas for cooling, for example,dry air at room temperature against the fins 166 a in the direction ofthe center of the outer circumferential wall 166, are provided in a loopat eight portions between the outer circumferential wall 166 and thecase 164. Each of the nozzles 167 is connected by an air supply duct176. When air is supplied from the outside of the casing 161, respectivedry air at the same wind speed are blown against the fins 166 a on theouter circumferential wall 166 from the respective nozzles 167.

[0080] The heat plate 170 supported by the support 165 is made of, forexample, aluminum and provided with a heater 171 generating heat by anelectric feed on the reverse thereof. Beneath the supporting stands 168which support the support 165, attached is a punched base plate 173provided with a large number of venting portions 172, such as a punchingmetal.

[0081] On the base plate 173, nozzles 174, which blow gas for cooling,for example, dry air at room temperature against the reverse side of theheat plate 170 in a vertical direction, are provided at eight positions.Each four of the nozzles 174 are concentrically arranged and thearrangement thereof is set not to overlap with the positions oftemperature sensors 175 for measuring a temperature of the heat plate170 (depicted by x in FIG. 11) when viewing its plane state. Each of thenozzles 174 is connected by the air supply duct 176 similarly to theabove-described nozzles 167 which blow gas against the fins 166 a on theouter circumferential wall 166, and respective air at the same windspeed is to be blown against the reverse side of the heat plate 170 fromthe respective nozzles 174 when air is supplied from the outside of thecasing 161.

[0082] On the heat plate 170, holes 182, through which three hoistingand lowering pins 181 for hoisting and lowering the wafer W project fromthe upper surface of the heat plate 170, are provided at three portions.Between the respective holes 182 and the base plate 173, verticallydisposed are respective cylindrical guides 183 for isolation anatmosphere from the nozzles 174 by covering the outer circumference ofthe hoisting and lowering pins 181. By virtue of these guides 183, thevertical movement of the hoisting and lowering pins 181 is not affectedby various cords or the like wired beneath the heat plate 170, andadditionally, the air blown from the nozzles 174 can be prevented fromdischarging through the holes 182 toward the wafer W. Incidentally,hoisting and lowering pins 181 are vertically movable by an appropriatedrive unit 184 such as an electric motor.

[0083] An appropriate exhaust port 164 a is provided on thecircumference of the lower portion of the case 164, while an appropriateexhaust port 161 a is also formed correspondingly on the side of thelower portion of the casing 161 in the post-exposure baking unit 141,and the exhaust port 161 a is connected with an exhaust duct 185 leadingto an exhaust portion (not shown) which intensively exhausts air fromother treatment units in the coating and developing system 1.

[0084] The post-exposure baking unit 141 according to the presentembodiment is structured as above and has a function of performingpost-exposure baking after exposure of pattern is carried out in analigner (not shown) adjacent to the coating and developing system 1.More specifically, the wafer W, of which exposing treatment iscompleted, is placed on the heat plate 170 by the hoisting and loweringpins 181, and thereafter the wafer W is heated to 140° C. by heating of,for example, the heater 171. Then, when heating of prescribed time isfinished, the hoisting and lowering pins 181 ascend to support the waferW. After that, the wafer W is sent to the main carrier unit 13 and thentransferred to the cooling unit 40.

[0085] Now, turning to a temperature of the post-exposure baking afterexposure varies corresponding to types of process, resist and so on. Infact, there is a case of not only heating at 140° C. as described above,but also heating at a lower temperature, for example, at 90° C. In thiscase, it is inevitable to quickly cool the heat plate 170 to makepreparations for heating at 90° C., and the post-exposure baking unit141 in the present embodiment can desirably cope with such lowering ofthe temperature of the heat plate 170.

[0086] To be more specific, after the completion of heat treatment ofthe wafer W which is the last one of a lot that is to undergo heattreatment at 140° C., air is supplied from the outside of the casing161, and through the air supply duct 176, air at room temperature isblown against the reverse side of the heat plate 170 from the nozzles174, and dry air at room temperature is similarly blown against the fins166 a on the outer circumferential wall 166 as shown in FIG. 12.

[0087] Then, the heat plate 170 and the outer circumferential wall 166of which heat efficiency is improved by forming fins 166 a thereon arecooled by the dry air at room temperature which is blown thereagainst.Accordingly, heat, which is accumulated in the outer circumferentialwall 166 while heat treatment is performed at 140° C., is diminished bythe blown air, whereby the temperature of the heat plate 170 can be morequickly lowered than the conventional type in which an outercircumferential wall 166 is not provided with groove portions 166 b andin addition air is not blown. Therefore, it takes less time to changesetting of temperature, resulting in the improvement of a throughput.

[0088] In the aforementioned embodiment, the groove portions 166 b onthe outer circumferential wall 166 can be provided with tubes 180 madeof, for example, aluminum with excellent heat conductivity, throughwhich fluid for cooling circulates, to cool the outer circumferentialwall 166, as shown in FIG. 13. Alternatively, only the tubes 180 may beprovided to have contact with the surface of the outer circumferentialwall 166 without providing such groove portions 166 b on the outercircumferential wall 166, which also makes it possible to more quicklydecrease heat accumulated in the outer circumferential wall 166,compared with the conventional one. Incidentally, both liquid such aswater and gas such as air may be used for fluid flowing in the tubes180. When air is used, air or dry air, which is supplied from the airsupply duct 176 and blown against the reverse side of the heat plate asdescribed above, may be used. As for material of tubes 180, a metal withexcellent heat conductivity, for example, aluminum is recommended.

[0089] It is preferable to make the cross-sectional shape of the grooveportions 166 b half-round to fit the shape of the outer circumference ofthe tubes 180 as shown in FIG. 14. Consequently, a contact area betweenthe surface of the tubes 180 and the surface of the groove portions 166b is expanded, which enables the outer circumferential wall 166 to becooled quickly.

[0090] Further, the cross-sectional shape of tubes 190 may be arectangle while the cross-sectional shape of the groove portions 166 bis kept rectangular as shown in FIG. 15. As a result, a contact areabetween the surface of the tubes 190 and the surface of the grooveportions 166 b is also expanded, which enables the outer circumferentialwall 166 to be cooled quickly.

[0091] Another example shown in FIG. 16 is that of the post-exposurebaking unit 141 having exhaust ducts 191 for exhausting an atmosphere inthe space section T below the heat plate 170 to the outside. In thiscase, the inside of the space section T below the heat plate 170 is aclosed space. When air is blown from the nozzles 174 to rapidly cool theheat plate 170, the atmosphere inside of the space section T isexhausted to the outside through the exhaust ducts 191. Consequently, itis possible to prevent particles from rising and contaminatingsurroundings thereof inside of the space section T. Incidentally, theexhaust ducts 191 are closed when the wafer is placed on the heat plate170 and heated. As a result, the atmosphere inside of the space sectionT can be prevented from leaking to the outside, whereby heatingefficiency of the heat plate 170 is improved.

[0092] Furthermore, a flow path 192, in which fluid for coolingcirculates, may be provided inside of the outer circumferential wall 166as shown in FIG. 17. Fluid for cooling, for example, dry air circulatesin the flow path 192, thereby enabling the outer circumferential wall166 to be efficiently cooled.

[0093] Incidentally, although the aforesaid embodiment is realized as aheat treatment unit capable of performing post-exposure baking, otherheat treatment units such as prebaking unit may naturally be employed.Further, although a substrate is the wafer in the above, it isapplicable to heat treatment units with other rectangular substrates,for example, an LCD substrate.

[0094] While the invention has been particularly shown and describedwith respect to preferred embodiments thereof by referring to theattached drawings, the present invention is not limited to theseexamples and it will be understood by those skilled in the art thatvarious changes in form and detail may be made therein without departingfrom the spirit, scope and teachings of the invention.

[0095] The entire disclosure of Japanese Patent Application No.11-278431 filed on Sep. 30, 1999 and Japanese Patent Application No.11-278438 filed on Sep. 30, 1999 including specification, claims,drawings and summary is incorporated herein by reference in itsentirety.

What is claimed is:
 1. A heat treatment unit in which a substrate isheated on a heat plate, comprising: a supporting member which supportsat least the peripheral portion of the heat plate; wherein material ofsaid supporting member is thermal insulating material.
 2. A heattreatment unit according to claim 1, wherein said supporting memberclosely contacts with said heat plate and supports the entirecircumference of the heat plate.
 3. A heat treatment unit according toclaim 2, wherein a space section is formed below said heat plate, and apart of members which form the space section is flexibly opened andclosed.
 4. A heat treatment unit according to claim 2, wherein materialof said heat plate is aluminum nitride.
 5. A heat treatment unitaccording to claim 2, wherein said heat plate has a heating elementprinted in a predetermined pattern.
 6. A heat treatment unit accordingto claim 3, further comprising an exhaust duct which exhausts anatmosphere inside of the space section.
 7. A heat treatment unit inwhich a substrate is heated on a heat plate, comprising: a supportingmember which supports at least the peripheral portion of the heat plate,material of said supporting member being thermal insulating material;and gas supply means for blowing gas for cooling against the reverseside of the heat plate.
 8. A heat treatment unit according to claim 7,wherein said supporting member closely contacts with said heat plate andsupports the entire circumference of the heat plate.
 9. A heat treatmentunit according to claim 8, wherein a space section is formed below saidheat plate and a part of members which form the space section isflexibly opened and closed.
 10. A heat treatment unit according to claim8, wherein material of said heat plate is aluminum nitride.
 11. A heattreatment unit according to claim 8, wherein said heat plate has aheating element printed in a predetermined pattern.
 12. A heat treatmentunit in which a substrate is heated on a heat plate, comprising: anouter circumferential wall surrounding the outer circumference of asupporting member which supports the heat plate; and a fin provided onthe surface of said outer circumferential wall.
 13. A heat treatmentunit according to claim 12, further comprising gas supply means forsupplying gas for cooling to said outer circumferential wall.
 14. A heattreatment unit according to claim 12, further comprising a tube in whichfluid for cooling circulates, between said fins.
 15. A heat treatmentunit according to claim 13, further comprising a nozzle which blows gasfor cooling against the reverse side of said heat plate.
 16. A heattreatment unit according to claim 14, further comprising a nozzle whichblows gas for cooling against the reverse side of said heat plate, gasfor cooling which circulates in said tube being the gas supplied to saidnozzle.
 17. A heat treatment unit according to claim 16, wherein the gasis dry air.
 18. A heat treatment unit according to claim 15, wherein gassupplied by said gas supply means is the gas which is supplied to saidnozzle.
 19. A heat treatment unit according to claim 18, wherein the gasis dry air.
 20. A heat treatment unit in which a substrate is heated ona heat plate, comprising: an outer circumferential wall surrounding theouter circumference of a supporting member which supports the heatplate; and a tube provided to have contact with the surface of the outercircumferential wall, in which fluid for cooling circulates.
 21. A heattreatment unit according to claim 20, further comprising a nozzle whichblows gas for cooling against the reverse side of said heat plate.
 22. Aheat treatment unit according to claim 21, wherein gas for cooling whichcirculates in said tube is the gas which is supplied to said nozzle. 23.A method of heating with a substrate placed on a heat plate, comprisingthe steps of: closing a space below the heat plate when the substrate isheated; and opening the space below the heat plate when the heat plateis cooled.
 24. A method according to claim 23, further comprising thestep of blowing gas against the reverse of said heat plate when the heatplate is cooled.